1. Technical Field of the Invention
The present invention relates to an apparatus for analysing the condition of a machine, and to a system for analysing the condition of a machine. The invention also relates to method of operating such a system.
2. Description of Related Art
Machines with moving parts are subject to wear with the passage of time, which often causes the condition of the machine to deteriorate. Examples of such machines with movable parts are motors, pumps, generators, compressors, lathes and CNC-machines. The movable parts may comprise a shaft and bearings.
In order to prevent machine failure, such machines should be subject to maintenance, depending on the condition of the machine. Therefore the operating condition of such a machine is preferably evaluated from time to time. The operating condition can be determined by measuring vibrations emanating from a bearing or by measuring temperature on the casing of the machine, which temperatures are dependent on the operating condition of the bearing. Such condition checks of machines with rotating or other moving parts are of great significance for safety and also for the length of the life of such machines. It is known to manually perform such measurements on machines. This ordinarily is done by an operator with the help of a measuring instrument performing measurements at measuring points on one or several machines.
A number of commercial instruments are available, which rely on the fact that defects in rolling-element bearings generate short pulses, usually called shock pulses. State of the art shock pulse measuring apparatuses may include proprietary technology for generating a value indicative of the condition of a bearing or a machine.
WO 98/01831 discloses a machine having a measuring point and a shalt with a certain shaft diameter, wherein the shaft can rotate when the machine is in use. WO 98/01831 also discloses an apparatus for analysing the condition of a machine having a rotating shaft. The disclosed apparatus has a sensor for producing a measured value indicating the vibration or temperature at the measuring point. The apparatus disclosed in WO 98/01831 has a microprocessor and an analysis routine stored in a memory. According to WO 98/01831 the following process can be performed by running the analysis routine on the microprocessor:                producing the measured value;        acquiring interpretation information from an information carrier which is mounted by the measuring point;        producing an actual condition value, indicating the actual condition of the machine at the measuring point, dependent on the measured value and the interpretation information;        acquiring a second condition value, indicating the condition of the machine at measuring point at an earlier point of time, from the information carrier;        producing a relation value dependent on the actual condition value and the second condition value, which relation value indicates a change in the condition.        